In the file 'assets/javascript/core.js', line 940 ('alt_text' callback), I think that the line:

$this.text(altText);

should be replaced by:

$this.children('span').text(altText);

... like in the 'toggle_link' callback, line 983, same file.

This callback seems to be used only by the "Bookmark topic" feature, and now, if you click on the corresponding menu item, the icon on the left disappears because all of the list line contents is replaced instead of only the text inside the "<span>" element, at least in the prosilver theme.

Of course this could now break other themes not based on prosilver, but otherwise the theme should set the whole alternative HTML snippet inside the data-alt-text attribute (styles/prosilver/template/.html, line 20), I don't even know if this is possible.

Gingko